Make pub strong-mode clean.

lib/src/command/global_activate.dart

 // Copyright (c) 2014, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 import 'dart:async';
 
 import 'package:pub_semver/pub_semver.dart';
 
 import '../command.dart';
 import '../utils.dart';
@@ skipping 17 matching lines @@
     argParser.addOption("executable", abbr: "x",
         help: "Executable(s) to place on PATH.",
         allowMultiple: true);
 
     argParser.addFlag("overwrite", negatable: false,
         help: "Overwrite executables from other packages with the same name.");
   }
 
   Future run() {
     // Default to `null`, which means all executables.
-    var executables;
+    List<String> executables;
     if (argResults.wasParsed("executable")) {
       if (argResults.wasParsed("no-executables")) {
         usageException("Cannot pass both --no-executables and --executable.");
       }
 
-      executables = argResults["executable"];
+      executables = argResults["executable"] as List<String>;
     } else if (argResults["no-executables"]) {
       // An empty list means no executables.
       executables = [];
     }
 
     var overwrite = argResults["overwrite"];
     var args = argResults.rest;
 
     readArg([String error]) {
       if (args.isEmpty) usageException(error);
@@ skipping 37 matching lines @@
       case "path":
         var path = readArg("No package to activate given.");
         validateNoExtraArgs();
         return globals.activatePath(path, executables,
             overwriteBinStubs: overwrite);
     }
 
     throw "unreachable";
   }
 }